Bring a large pot of salted water to a boil, add rigatoni and cook for 8-10 minutes until al dente. Reserve 1 cup of pasta water before draining.

Drain the rigatoni and set aside.

In a large skillet, heat olive oil over medium heat. Sauté diced onion for 4-5 minutes until translucent.

Add minced garlic and sauté for an additional minute until fragrant.

Crumble the Italian sausage into the skillet and cook for 6-8 minutes until browned.

Mix in the canned tomatoes and bring to a simmer. Cook for about 15 minutes.

Season with red chili flakes, salt, and pepper to taste.

Lower the heat and gradually stir in the heavy cream, letting it simmer for 5-7 minutes until slightly thickened.

Stir in the grated Parmesan cheese until melted. Adjust consistency with reserved pasta water if needed.

Add the drained rigatoni to the skillet, tossing to coat well with the sauce.

Plate and garnish with additional Parmesan cheese and fresh basil. Serve hot.